uinput: use the UI_GET_SYSNAME ioctl if available

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>

2 files changed, 20 insertions, 15 deletions

diff --git a/libevdev/libevdev-uinput.c b/libevdev/libevdev-uinput.c
index e0ae31e..f8607d1 100644
--- a/libevdev/libevdev-uinput.c
+++ b/libevdev/libevdev-uinput.c
@@ -198,8 +198,17 @@ fetch_syspath_and_devnode(struct libevdev_uinput *uinput_dev)
 {
 	struct dirent **namelist;
 	int ndev, i;
-
-	/* FIXME: use new ioctl() here once kernel supports it */
+	int rc;
+	char buf[sizeof(SYS_INPUT_DIR) + 64] = SYS_INPUT_DIR;
+
+	rc = ioctl(uinput_dev->fd,
+		   UI_GET_SYSNAME(sizeof(buf) - strlen(SYS_INPUT_DIR)),
+		   &buf[strlen(SYS_INPUT_DIR)]);
+	if (rc != -1) {
+		uinput_dev->syspath = strdup(buf);
+		uinput_dev->devnode = fetch_device_node(buf);
+		return 0;
+	}
 
 	ndev = scandir(SYS_INPUT_DIR, &namelist, is_input_device, alphasort);
 	if (ndev <= 0)
@@ -207,7 +216,6 @@ fetch_syspath_and_devnode(struct libevdev_uinput *uinput_dev)
 
 	for (i = 0; i < ndev; i++) {
 		int fd, len;
-		char buf[sizeof(SYS_INPUT_DIR) + 64];
 		struct stat st;
 
 		strcpy(buf, SYS_INPUT_DIR);
diff --git a/libevdev/libevdev-uinput.h b/libevdev/libevdev-uinput.h
index fa3eae7..3212628 100644
--- a/libevdev/libevdev-uinput.h
+++ b/libevdev/libevdev-uinput.h
@@ -176,17 +176,14 @@ int libevdev_uinput_get_fd(const struct libevdev_uinput *uinput_dev);
 /**
  * @ingroup uinput
  *
- * Return the syspath representing this uinput device.
- * At the time of writing, the uinput kernel device does not
- * provide a way to get the syspath directly through uinput so libevdev must guess.
- * In some cases libevdev is unable to derive the syspath. If the running kernel
- * supports the UI_GET_SYSNAME ioctl, the syspath is retrieved through that and will
- * be reliable and not be NULL. The UI_GET_SYSNAME ioctl is currently
- * scheduled for 3.15.
- *
- * @note This function may return NULL. libevdev currently uses ctime and
- * the device name to guess devices. To avoid false positives, wait at least
- * wait at least 1.5s between creating devices that have the same name.
+ * Return the syspath representing this uinput device. If the UI_GET_SYSNAME
+ * ioctl not available, libevdev makes an educated guess.
+ * The UI_GET_SYSNAME ioctl is available since Linux 3.15.
+ *
+ * @note This function may return NULL if UI_GET_SYSNAME is not available.
+ * In that case, libevdev uses ctime and the device name to guess devices.
+ * To avoid false positives, wait at least wait at least 1.5s between
+ * creating devices that have the same name.
  * @param uinput_dev A previously created uinput device.
  * @return The syspath for this device, including the preceding /sys
  *
@@ -202,7 +199,7 @@ const char* libevdev_uinput_get_syspath(struct libevdev_uinput *uinput_dev);
  * This relies on libevdev_uinput_get_syspath() to provide a valid syspath.
  * See libevdev_uinput_get_syspath() for more details.
  *
- * @note This function may return NULL. libevdev currently has to guess the
+ * @note This function may return NULL. libevdev may have to guess the
  * syspath and the device node. See libevdev_uinput_get_syspath() for details.
  * @param uinput_dev A previously created uinput device.
  * @return The device node for this device, in the form of /dev/input/eventN